Pulmonary embolism (PE) affects many, with an estimated incidence of up to 69 cases per 100,000 persons annually. In the U.S., 101,000 patients were hospitalized with a primary diagnosis of PE in 2002, resulting in direct medical costs of $720 million. Outpatient treatment with low-molecular-weight heparin (LMWH) may be an effective and safe option for up to 50% of patients with non-massive PE. Despite this evidence, outpatient treatment of PE is extremely rare because (1) explicit criteria that identify patients who are at low-risk of adverse medical outcomes were not available until recently, and (2) limited data defining the safety and effectiveness exists. We previously developed a clinical prognostic model that accurately identifies patients with PE who are at low-risk for short-term mortality, symptomatic recurrent PE (primary outcome) or venous thromboembolism (VTE) and major bleeding (secondary outcomes). The broad objective of this clinical trial is to address the other major barrier to outpatient treatment of low-risk patients with non-massive PE, the effectiveness and safety of outpatient management. We will randomize 320 low-risk patients (identified using our prognostic model) with PE from 10 hospital emergency departments in the U.S. and Western Europe to receive outpatient or inpatient treatment with LMWH for =5 days, followed by oral anticoagulation. The specific aims of the project are to compare (1) the frequency of re-current PE, (2) the frequency of recurrent VTE, major bleeding and all-cause mortality, and (3) medical resource utilization and patient satisfaction with care among patients randomized to receive outpatient or inpatient treatment with LMWH. The study outcomes and all cause mortality will be assessed at 3 months. We hypothesize that out-patient treatment with LMWH is as effective and safe as inpatient treatment with LMWH, and is associated with reduced medical resource utilization and increase patient satisfaction with care. Our innovative design translates a validated prognostic model into clinical practice and addresses a key barrier to effective, less costly care of select patients with PE.